Last month we discussed the "zero-zero" landing, an emergency-only procedure that can be used when a pilot paints himself into a corner and is left with no option other than to attempt an approach and landing when the visibility is nil.
The flip side of this coin is the "zero-zero" or instrument takeoff (ITO), which is somewhat of a misnomer. A pilot must have at least 50 to 100 feet of visibility to find, taxi onto, and line up with the runway.
Although a zero-zero landing is not an approved procedure, the instrument takeoff has the FAA's blessing as long as the pilot operates under FAR Part 91. (Those flying for hire must abide by published takeoff minimums.) But just because it is legal for a private pilot to operate in conditions that keep air carriers grounded and sea gulls walking does not necessarily mean that it is safe.
The world's worst aviation disaster (in terms of lives lost) occurred on a fog-shrouded runway at Tenerife in the Canary Islands when a departing KLM Boeing 747 slammed headlong into a Pan American Airlines 747 taxiing across the active runway. Years earlier, a TWA Boeing 707 cargo flight departing Tel Aviv on a foggy night collided with a military KC-97 being towed across the runway.
Obstructions on the runway, such as other aircraft and ground vehicles that might have lost their way in the fog, probably represent the greatest hazard associated with zero-zero and low-visibility takeoffs. When a pilot shoves the throttle to the firewall, he assumes that the runway is clear—an assumption for which there may be no basis (especially at uncontrolled airports). Consider also that a takeoff clearance issued by a tower controller means only that the runway is clear of known traffic. In this respect, I have never been comfortable with a low-visibility takeoff unless most of the runway is visible.
There are, of course, other hazards associated with a takeoff that require a pilot to fly on instruments before liftoff. One of the most obvious is the difficulty he might have in maintaining runway alignment. Another is that the airport would not be available for a return landing should a problem develop shortly after takeoff. For this reason, some pilots never make an instrument departure unless the weather is at landing minimums. Another consideration should be that an engine failure shortly after a low-visibility liftoff might necessitate a forced landing in zero-zero conditions, a less-than-enviable predicament. Yet another hazard is the potential for losing control during the transition from liftoff to climb.
Many instrument instructors train their IFR students to execute instrument takeoffs while wearing a vision-limiting device. Unfortunately, this is not a difficult maneuver to master. I say unfortunately because this leads new instrument pilots to believe that a zero-zero takeoff is easier and safer than it really is. In this case, there is a world of difference between actual and simulated.
An instrument takeoff obviously begins visually. As speed increases, however, keeping the runway centerline in sight can become more difficult or even impossible (especially in rain or snow), and the pilot must transition from visual to instrument "flying" during the takeoff roll. This sudden and unexpected change of reference can lead to spatial disorientation and loss of control. It is similar to the onset of vertigo that can develop when taking off in VFR conditions on a moonless night toward a "black hole" (such as a large body of water) when the horizon is not visible.
If a pilot is determined to make a zero-zero or low-visibility takeoff, he might consider the following advice:
- Be certain that preflight preparations are extraordinarily thorough because you might be on instruments within seconds of brake release. This includes turning on the pitot heat before takeoff.
- When taxiing into position, allow the aircraft to roll along the centerline to ensure that the nosewheel is pointed straight ahead. Bring the aircraft to a stop and take a deep breath. Do not rush.
- Carefully set the heading bug so that it points straight ahead, which might not be exactly the same as the runway heading. Without a bug, set the direction indicator to the nearest 10 degrees, which is easier to maintain than an odd number of degrees.
- Before adding power, double-check all instruments. Then ask yourself if this flight is really that important and whether you are exercising good risk management.
- After brake release, ensure that maximum power is set prior to losing sight of the centerline so that increasing power does not require additional rudder compensation while steering on instruments.
- Concentrate on holding a precise heading with nosewheel steering and resist the temptation to look outside or turn your head to one side, which can induce vertigo.
- Use normal rotation techniques at a slightly higher-than-normal airspeed with the wings held level. Establish a climb attitude and hold it. Do not lower the nose so much as one degree when near the ground. Delay making configuration changes, do not turn, do not look at a chart, do not do anything other than to maintain a safe attitude until reaching 300 feet agl.
Sound easy? Believe me, it is not.
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